1. Field of the Invention
The present invention relates to an anti-roll system for a vehicle and, more particularly, to an anti-roll system for a vehicle that does not geometrically interfere with an existing suspension system and can change roll-controlling efficiency easily in accordance with roll stiffness.
2. Description of Related Art
In a steerable front wheel suspension, the suspension should be designed to absorb vibration or impact from the road surface as well as obtain running safety by maintaining an optimal position of a vehicle's straight ahead position and handling safety of a vehicle's turning position.
Stability of the vehicle is closely related to the vibration of the vehicle body during the vehicle's running, rolling, pitching, and yawing in addition to bounce. These vibrations should be absorbed to increase the stability and ride comfort of the vehicle.
In such vibrations, the rolling occurs at a predetermined point when the vehicle is in a turning situation, and this point is called a roll center. The variation rate of the roll center's height has an effect on the running safety and handling safety of the vehicle. Accordingly, to achieve running safety, it is more desirable to decrease the variation rate of the roll center's height.
There have been used well-known stabilizer bars as means for controlling roll generated naturally during the vehicle's running.
A stabilizer bar 70 is a kind of a torsion bar including a bent portion 71 having both ends bent to one side as shown in FIG. 5A.
If the stabilizer bar 70 is applied to a vehicle, it is disposed in the horizontal direction against the vehicle body, as shown in FIG. 5B. Its midpoint is fixed to the vehicle body or sub-frame. The end of the bent portion is fixed to a lower control arm 73 of a suspension system 72.
Accordingly, when the lower control arm 73 vibrates upward and downward by the up-and-down vibration of the wheel, the anti-roll system of the present invention may control rolling by minimizing the slant of the vehicle body by means of a self-elastic force of the stabilizer bar 70.
The conventional anti-roll system adopts a stabilizer bar having a small spring characteristic to attain good riding comfort but anti-roll function is not satisfactorily achieved because of centrifugal force encountered during the vehicle's turning.
On the contrary, if the stabilizer bar has a large spring characteristic, a geometrical interference of the suspension system is generated and riding comfort is deteriorated.
The stabilizer bar as mentioned above, has a limited spring characteristic, and the spring characteristic is not changeable until the stabilizer bar is replaced with another, which results in difficulties.